In general, a biochip is a biological microchip manufactured as bio-molecules such as DNA, proteins etc. are combined with blood or urine of a tester on a relatively small substrate so that generic defects, protein distributions, reaction aspects etc. can be analyzed. Biochips have attracted attention in fields such as pharmaceutical development, environment monitoring, etc. as well as clinical diagnosis such that marketability is highly evaluated in the future. In order that such a biochip is utilized for a sensor for diagnosis and monitoring of environments/foods etc., it is preferably implemented with a type of biosensor capable of being easily portable and directly analyzing samples at the work field. Therefore, it is necessary to develop biochips such that they have a relatively high processing speed and low manufacturing costs. Also, it is very important to form First-to-market in the biochip fields. Because biochips are used not only in the laboratory but also in information construction for a database, if a product introduced before generally selling on a market constructs a database and gets to be a standard based on the constructed database, it is difficult to replace the product having been a standard with another product in that market. Therefore, based on the aspect, certain companies having previously occupied the biochip fields have great advantages. The biochip markets are formed in the mid-1990s and rapidly raised around in the center of some product- and service-oriented companies in these days, but it is still an initial stage considering the entire technology. Therefore, this field needs to be continuously researched through novel ideas.
In one analysis method using biochips, blood or urine etc. of a testee is reacted with a biochip integrated with protein and florescent dye responding to a particular disease or symptom. After that the method diagnoses whether the testee has the particular disease or symptom as fluorescent dye revealed by activated between the proteins of the biochip and the proteins included in the blood or urine are analyzed. The biochip for diagnosing a particular disease or symptom is called as a diagnosis kit. The diagnosis kits may be categorized based on promptness and precision. Generally, biochips are analyzed by naked eye or under a microscope. However, the bio-chip test by naked eye requires a relatively high skillful experience of the examiners because it is dependent on only his/her determination. Therefore, reliability of the bio-chip analysis results may be decreased due to examiner error. Also, precision of the analysis results may be decreased by internal or external factors such as examiner fatigue, analysis environments, etc. Meanwhile, even though the microscopic test has a higher reliability than the test by naked-eye of the examiner, it requests much examining time and examiners.
Generally, biochip manufacturing methods are classified into micro-array and micro-fluidics.
{circle around (1)} Micro-array:
It is typically used for a DNA chip, a protein chip, etc., in which they are constructed as thousands or tens of thousands of DNAs or proteins etc. are evenly aligned and spaced from each other to attached on a substrate such that coupling aspects thereof can be analyzed based on a processing operation of targeted analysis materials. The protein chip has more valuable than the relatively well-known DNA chip considering that most biological phenomena occurs at the protein level. But, unlike DNA, the protein chip has less developed and commercialized than the DNA chip due to difficulty in securing corresponding proteins such as enzymes, antibodies, receptors, etc. and the easily changeable and denaturable nature of proteins.
{circle around (2)} Micro-fluidics Manner:
The micro-fluidics manner is also called ‘Lab-on-a-Chip’. It is used for biochips capable of analyzing aspects reacting with various bio molecules or sensors, which are integrated with a chip while a small quantity of targeted analysis materials are flowing. Recently, chips capable of performing separation of analysis material, synthesis, quantitative analysis etc. have been researched.
Biochips manufactured by the above-mentioned manners are aligned according to desired location information, respectively, and detected by a method for labeling florescent dye. The sample solution labeled by the fluorescent dye and the bio-information fixed to the substrate are reacted to each other under general coupling reaction conditions so as to monitor the degree of selective coupling.
Such biochips are typically detected by laser induced fluorescing detection. Laser induced fluorescing detection is performed like that fluorescent dye is excited as the florescent dye absorbs light emitted from a light source, in which the light source emits the laser beam at a wavelength capable of being absorbed by the fluorescent dye, and then the amount of fluorescence emitted when the fluorescent dye changes from the excited state to the ground state is measured, thereby determining density thereof from each of the fluorescence intensities. Based on the method, a DNA sample can be quantitatively analyzed when fluorescent dye is added thereto. One of the most commonly used apparatuses for detecting fluorescence using the laser induced fluorescing detection method is a confocal laser scanning system. The confocal laser scanning system employs a laser as a light source and inputs fluorescent signals emitted from a sample through a specific detector such as a photomultiplier tube or an avalanche photo diode to convert the fluorescent signals into a digital image. Namely, fluorescence emission is induced as only light emitted from a laser source is scanned to a sample labeled by fluorescent dye, in which the wavelength band of the light emitted from the laser source is proper to excite the fluorescent dye. Here, various filters such as a beam splitter etc. can be used. At the last stage, a pinhole as a filter can be located in front of a detector such that only a confocal image is received. As such, the confocal laser scanning system requires a preferable selection etc. and has an advantage in that out of focus images can be eliminated. At the present stage of development, it is important to advance sensitivity of a fluorescence detection device in a laser induced fluorescing detection apparatus and a technology therefor. One of the major factors to advance the sensitivity of the fluorescence detection device is to collect maximum fluorescence radiation and to minimize background radiation. Therefore, in order to obtain an optimal detection limit in the laser induced fluorescing detection apparatus, fluorescence emitted from a test sample labeled by fluorescent dye should be collected with a high efficiency and distribution of excited light reaching the fluorescence detection device can be minimized. Substantially, an objective lens having a relatively high aperture or a mirror is used for fluorescence collection. Light collection by a lens is related to aperture of the lens and refraction index of peripheral media. Such a relationship can be expressed by the following equation (1).
                              Collection          ⁢                                          ⁢          efficiency                =                              1            2                    ⁢                      (                                          1                -                                  cos                  ⁡                                      (                                                                  sin                                                  -                          1                                                                    ⁡                                              (                        NA                        )                                                              )                                                              =                                                1                  2                                ⁢                                  (                                      1                    -                                          cos                      ⁡                                              (                                                                              sin                                                          -                              1                                                                                ⁡                                                      (                                                          1                                                              2                                ⁢                                F                                                                                      )                                                                          )                                                                                                                                                    (        1        )            
Where F denotes numerical aperture (F-number) and NA denotes effective numerical aperture.
Generally, a light collection lens is surrounded by air, which has a refractive modulus of 1. From the above equation (1), it can be easily appreciated that a lens having a relatively large numerical aperture is required to obtain high collection efficiency. For example, if a lens has a numerical aperture of 1, it can collect 50% of light emitted from the test sample. Also, according to the collection efficiency equation, a lens surrounded by air with a numerical aperture of 0.5 can collect only 7% of emitted light.
In the prior art refractive or reflective optical collectors having optical fibers are used for collecting emitted fluorescence radiation. However, fluorescent light collection efficiency of these collectors is limited by their maximum collection angle. As shown in FIG. 25, a typical highly efficient collector has a collection cone angle of about 90° , which corresponds to a collection efficiency of 14% in the laser induced fluorescing detection apparatus.
Even though such a confocal laser scanning system has a high sensitivity and precision, it is expensive and occupies a large volume for installation.
Especially, in the confocal laser scanning system, since a chip for requiring an accuracy of less than 1 μm or monitoring large amounts of information is proper to used therefor, a biochip is difficult to be generally adopted therein.
Also, since the confocal laser scanning system scans fluorescent images and then displays images corresponding to the fluorescent images, it has disadvantages in that it requires much processing time such as scanning time and analysis time.
Also, chips manufactured by the prior art methods are evenly aligned row by row and patterned in a land/groove manner using XY linear stages. However, in order to construct disc-type biochips, the prior art methods must be designed for patterning the biochips along the periphery of the disc thereon.